An intrauterine device (IUD) is a small, often T-shaped device, containing copper or hormone (e.g., Levonorgestrel), which is inserted into the uterus to provide long-acting, reversible contraception. Intrauterine devices are the most widely used form of reversible contraception, with more than 180 million users worldwide.
Copper IUDs primarily work by disrupting sperm mobility and damaging sperm so that the sperm are prevented from joining with an egg. Copper acts as a spermicide within the uterus, increasing levels of copper ions, prostaglandins, and white blood cells within the uterine and tubal fluids. The increased copper ions in the cervical mucus inhibit the sperm's motility and viability, preventing sperm from traveling through the cervical mucus or destroying it as it passes through. Copper IUDs have a first-year pregnancy-prevention success rate ranging from 97.8 to 99.9 percent. The Paragard® intrauterine copper contraceptive device (www.paragard.com) is currently the most common copper IUD. Copper IUDs can typically be implanted for up to 10 years.
Advantages of the copper IUD include its ability to provide emergency contraception up to five days after unprotected sex. It is generally known as the most effective form of emergency contraception available. It contains no hormones, so it can be used while breast feeding, and fertility returns quickly after removal. Copper IUDs are also available in a wider range of sizes and shapes than hormonal IUDs. Disadvantages include the possibility of heavier menstrual periods and more painful menstrual cramping.
A hormonal IUD, such as the Mirena® levonorgestrel-releasing intrauterine system (www.mirena-us.com), uses the controlled release of a hormonal contraceptive such as levonorgestrel (a progestin). The hormonal contraceptive released from a hormonal IUD prevents ovulation from occurring, so an egg is never released. The hormone also thickens the cervical mucus so that sperm cannot reach the fallopian tubes. Hormonal IUDs can be implanted for up to 5 years.
Hormonal IUDs do not increase bleeding as copper-containing IUDs do. Instead, they can often reduce menstrual bleeding or prevent menstruation altogether, and thus they are sometimes used as a treatment for menorrhagia (heavy menstrual bleeding). Hormonal IUDs do have common side effects, however. The most common side effects with levonorgestrel IUDs are hormone-related effects, such as headaches, nausea, breast tenderness, depression and cyst formation.
Regardless of the contraceptive mechanism, IUDs almost always include one or two threads, which are attached at the distal (cervical) end of the IUD, and which have two uses. First, the IUD thread is used to remove the IUD when desired, by the physician pulling on the thread to dislodge the IUD from the uterus and pull it through the cervix and out the vaginal cavity. For this purpose, the thread must be long enough to traverse the cervical canal and extend into the vaginal cavity. Second, the thread is used to confirm that the IUD is still in place. This is done either by the physician on vaginal exam or by the women herself feeling the thread with her finger. Third, the thread is currently used to load the IUD into the IUD insertion device and secure it within the inserter during advancement of the distal end of the inserter into the uterus. Because the thread is used for loading and securing the IUD in the inserter, it must be long enough to extend through the inserter to its proximal end. This means that the thread must be much longer than it would need to be if used only for IUD retrieval or verification. Thus, currently available IUD systems require the physician to insert sterile, sharp scissors or another cutting instrument into the vaginal cavity after IUD placement and cut the extra-long thread to a useful length for later IUD retrieval. It is not practical to leave the IUD thread uncut, because it would extend out of the vagina, causing physical discomfort to the user, discomfort during sexual intercourse, significant risk of infection, and significant risk of accidental removal of the IUD by pulling on the dangling thread.
Therefore, after an IUD is delivered into the uterus, the IUD insertion device is removed from the body, leaving the IUD in the uterus and the long thread extending through the cervix into the vaginal cavity. The physician must then insert sterile scissors into the vaginal cavity to cut the thread to a shorter length, so that the thread still extends into the vaginal cavity but does not extend too far into or out of the vaginal cavity. The remaining end portion of the thread then typically wraps around the cervical fornix.
Although currently available IUD threads work for their intended purpose, inserting the IUD requires additional time and the additional step of trimming the thread. This step involves inserting scissors or some other sharp cutting device into the vaginal cavity, which adds time and potential discomfort to an IUD insertion procedure and increases the risk of accidentally dislodging the IUD from the uterus. In a worst case scenario, the thread cutting step may even cause injury and/or infection to the patient, due to the required insertion and manipulation of a sharp cutting device in the vaginal cavity. Therefore, it would be advantageous to have an IUD device with an improved thread or other retrieval mechanism that did not require trimming or other, additional steps during an IUD insertion procedure.